I have an extra monitor which is connected to my MacBook Pro 13 2020 using a USB-C to VGA convertor. Is it safe to unplug the extra screen without turning off the monitor? Because when I plugged in the charger, the extra monitor turned off for two seconds.
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3HDMI or DP is OK. With VGA really not recommended even with the USB-C adapter.– ChanganAutoCommented Aug 21, 2021 at 12:13
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8Does this answer your question? Is VGA port hot-pluggable?– JoeCommented Aug 22, 2021 at 4:42
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3VGA? what year is this?– njzk2Commented Aug 22, 2021 at 16:35
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3@njzk2 The large majority of server class systems use a VGA output. The few that don't are a major annoyance to server administrators. Server class also includes enterprise storage and network systems.– doneal24Commented Aug 22, 2021 at 18:07
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4In the data centers I visit, we hot plug VGA all the time from crash carts; it has never occurred to me that I could cause damage (other than physical by not inserting a plug in straight) to a system by hot plugging in a VGA connection.– RandallCommented Aug 24, 2021 at 12:22
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2 Answers
Best practice is to always power off any devices that are not designed to be hot-pluggable before disconnecting them. VGA is not hot-pluggable, therefore its cables are not designed to be disconnected while powered.
That being said, in reality, it is perfectly safe. While you don’t see VGA being used much these days, it was far more common 15-20+ years ago. I have physically disconnected and reconnected hundreds of live VGA connections with not a single issue.
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5The question OP is using a USB-C to VGA convertor. USB is designed to be hot-pluggable (at least from a hardware POV). While the converter may not be doing the "right thing", it should be making it such that the USB-C connector (not necessarily the VGA connector) can be plugged in or out without any need to be concerned about the monitor power being off or on. OTOH, your statement about best practices is on the money.– MakyenCommented Aug 22, 2021 at 16:58
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@Makyen While USB is hot-pluggable, that doesnt make the device itself hot-pluggable. Take a USB disk drive, as an example. You could physically pull the USB connector out, knowing you wont damage the hardware, but data could be lost. Not a big deal for a VGA monitor. However, using any adapter for a device that was not designed for it, you run a risk that something could go wrong.– KeltariCommented Feb 11, 2023 at 17:35
Some monitors might have problems with incorrect timing. (I don't want to describe how CRT and LCD monitors work, etc. See Wikipedia pages or OSDev for that.)
Some monitors, both CRT and LCD, according to OSDev Wiki page (the big bold red warning at the top of the page) can have problems with wrong timing information and disconnecting the VGA connector can make some pins to lose connection before others and that could possibly even damage the monitor.
Well, it is quite safe (at least for newer monitors), and, if you need to do that, disconnect the monitor. All LCD monitors I've used do support hot plug, or, at least, work well when they are disconnected while running. I've seen (and “repaired”) monitor that was fed using connector with dirty horizontal sync pin. It was displaying funny pictures, but it did not get damaged.
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3I think millions of people must have plugged in a VGA monitor with a bad cable, once upon a time, and never once damaged the monitor in the process - a new/good cable always works fine, no matter how weird the picture was with the bad one.– MikeBCommented Aug 24, 2021 at 15:21
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The damage is possible, but the probability of it is very low. I think that it is impossible for modern monitors, but some monitors were very sensitive to wrong timing.– jiwopeneCommented Aug 25, 2021 at 16:03